Uranium dating zircon
Uranium dating zircon - boundaries in dating curriculum
Zircon is also remarkably dense and exhibits a very pronounced level of birefringence.
Zircon can also be easily distinguished by its notable birefringence; when looking down through the table of a stone, the doubling effect of facet edges can be easily seen.Green zircon is very rare and owes its color to minute natural traces of uranium and thorium. Zircon belongs to the large group of minerals known as neosilicates that contain both silicon and oxygen in their composition.The neosilicate group includes varieties of beryl and garnet, andalusite, kyanite, olivine (peridot), tanzanite, topaz, tourmaline and quartz.It is the oldest mineral on Earth, with samples found in Australia that are over 4.4 billion years old.Scientists discovered that zircon actually contains trace elements of uranium and thorium, both of which are elements with known half-lives.Most zircon deposits come from Burma, though Australia boasts the oldest deposits dating back more over 4.4 billion years.
Other notable sources include Brazil, Korea, Madagascar, Mozambique, Nigeria, Tanzania, Thailand and Vietnam.Blue is the most popular, but its color is obtained through the heating of brown zircon, usually from Cambodia and Burma. Zircon with cat's eye chatoyancy is known but very rare.Due to pleochroism, blue zircon can look greenish from certain angles. Green zircon is very rare and typically very expensive. Some crystals contain radioactive elements of thorium and uranium.Blue zircon is actually produced by heating more commonly occurring brown zircon.However, only some brown materials have the appropriate physical structure to turn blue when heated, typically only deposits found in South East Asia - which is why most blue zircon comes from Cambodia or Burma.Zircon in its purest form is completely colorless (white), but owing to trace impurities, it can occur in a wide range of interesting colors, including yellow, orange, red, green, blue, violet, brown and combinations in between.